Heat exchanger for an aircraft

ABSTRACT

A heat exchanger for an aircraft includes an inlet plenum housing defining an inlet plenum configured to receive a fluid and an outlet plenum housing defining an outlet plenum configured to discharge the fluid. Furthermore, the heat exchanger includes a core configured to heat or cool a first portion of the fluid, with the core defining a plurality of fluid passages extending from the inlet plenum to the outlet plenum. Moreover, the heat exchanger includes a passive bypass defining a passive bypass flow path fluidly coupled to and extending between the inlet plenum and the outlet plenum. As such, the passive bypass flow path is in parallel with at least a portion of the core such that a second portion of the fluid bypasses at least a portion of the core and flows continuously and unobstructed through the passive bypass flow path to the outlet plenum.

FIELD

The present subject matter relates to aircraft and, more particularly,to heat exchangers for an aircraft or an associated gas turbine engine.

BACKGROUND

A turbofan engine generally includes a fan, a compressor section, acombustion section, and a turbine section. More specifically, the fangenerates a flow of pressurized air. A portion of this air flow is usedas propulsive thrust for propelling an aircraft, while the remaining airis supplied to the compressor section. The compressor section, in turn,progressively increases the pressure of the received air and suppliesthis compressed air to the combustion section. The compressed air and afuel mix within the combustion section and burn within a combustionchamber to generate high-pressure and high-temperature combustion gases.The combustion gases flow through the turbine section before exiting theengine. In this respect, the turbine section converts energy from thecombustion gases into rotational energy. This rotational energy, inturn, is used to drive the compressor section and/or the fan via variousshaft and/or gearboxes.

Typically, a turbofan engine includes various heat exchangers to heat orcool the fluids that support the operation of the engine and/or theassociated aircraft. For example, the engine may include one or moreheat exchangers that cool the oil circulated through the gearbox(es) ofthe engine.

In general, there is a trade-off between the pressure drop of the fluidflowing through the heat exchanger and the heat transfer from or to suchfluid. More specifically, as the amount of heat transfer to or form thefluid flowing through the heat exchanger increases, so does the pressuredrop across the heat exchanger. As such, it typically necessary toincrease the size and the weight of the heat exchanger to keep thepressure drop under a maximum value while maintaining a minimum heattransfer rate. Increased heat exchanger size and weight may negativelyimpact the performance or efficiency of gas turbine engines and/oraircraft.

Accordingly, an improved heat exchanger for an aircraft or an associatedgas turbine engine would be welcomed in the technology.

BRIEF DESCRIPTION

Aspects and advantages of the invention will be set forth in part in thefollowing description, or may be obvious from the description, or may belearned through practice of the invention.

In one aspect, the present subject matter is directed to a heatexchanger for an aircraft. The heat exchanger includes an inlet plenumhousing defining an inlet plenum configured to receive a fluid and anoutlet plenum housing defining an outlet plenum configured to dischargethe fluid from the heat exchanger. Furthermore, the heat exchangerincludes a core configured to heat or cool a first portion of the fluid,with the core defining a plurality of fluid passages fluidly coupled toand extending from the inlet plenum to the outlet plenum. Moreover, theheat exchanger includes a passive bypass defining a passive bypass flowpath fluidly coupled to and extending between the inlet plenum and theoutlet plenum. As such, the passive bypass flow path is in parallel withat least a portion of the core such that a second portion of the fluidbypasses at least a portion of the core and flows continuously andunobstructed through the passive bypass flow path to the outlet plenum.

In another aspect, the present subject matter is directed to a gasturbine engine. The gas turbine engine includes a compressor, acombustor, a turbine, and a heat exchanger in operative association withat least one of the compressor, the combustor, or the turbine. The heatexchanger, in turn, includes an inlet plenum housing defining an inletplenum configured to receive a fluid and an outlet plenum housingdefining an outlet plenum configured to discharge the fluid from theheat exchanger. Additionally, the heat exchanger includes a coreconfigured to heat or cool a first portion of the fluid, with the coredefining a plurality of fluid passages fluidly coupled to and extendingfrom the inlet plenum to the outlet plenum. Furthermore, the heatexchanger includes a passive bypass defining a passive bypass flow pathfluidly coupled to and extending between the inlet plenum and the outletplenum. In this respect, the passive bypass flow path being in parallelwith at least a portion of the core such that a second portion of thefluid bypasses at least a portion of the core and flows continuously andunobstructed through the passive bypass flow path to the outlet plenum.

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdescription and appended claims. The accompanying drawings, which areincorporated in and constitute a part of this specification, illustrateembodiments of the invention and, together with the description, serveto explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth in the specification, which makes reference to the appendedfigures, in which:

FIG. 1 is a side view of one embodiment of an aircraft;

FIG. 2 is a schematic cross-sectional view of one embodiment of a gasturbine engine of an aircraft;

FIG. 3 is a schematic view of one embodiment of a heat exchanger for anaircraft;

FIG. 4 is a schematic view of another embodiment of a heat exchanger foran aircraft;

FIG. 5 is a diagrammatic view of one embodiment of a heat exchanger foran aircraft;

FIG. 6 is a partial cross-sectional view of the heat exchanger shown inFIG. 5, illustrating an inlet plenum and a passive bypass of the heatexchanger;

FIG. 7 is another partial cross-sectional view of the heat exchangershown in FIGS. 5 and 6, illustrating one embodiment of a passive bypassflow path of the passive bypass;

FIG. 8 is a further partial cross-sectional view of the heat exchangershown in FIGS. 5 and 6, illustrating another embodiment of a passivebypass flow path of the passive bypass;

FIG. 9 is yet another partial cross-sectional view of the heat exchangershown in FIGS. 5 and 6, illustrating a further embodiment of a passivebypass flow path of the passive bypass;

FIG. 10 is a top view of another embodiment of a heat exchanger for anaircraft;

FIG. 11 is a cross-sectional view of the heat exchanger shown in FIG. 10generally taken about Line 10-10;

FIG. 12 is a top view of a further embodiment of a heat exchanger for anaircraft;

FIG. 13 is a cross-sectional view of the heat exchanger shown in FIG. 12generally taken about Line 13-13;

FIG. 14 is a diagrammatic view of yet another embodiment of a heatexchanger for an aircraft;

FIG. 15 is a cross-sectional view of the heat exchanger shown in FIG. 14generally taken about Line 15-15;

FIG. 16 is a top view of yet a further embodiment of a heat exchangerfor an aircraft;

FIG. 17 is a top view of another embodiment of a heat exchanger for anaircraft;

FIG. 18 is a cross-sectional view of the heat exchanger shown in FIG. 17generally taken about Line 18-18, illustrating one embodiment of aplurality of bypass passage flow paths; and

FIG. 19 is a cross-sectional view of the heat exchanger shown in FIG. 17generally taken about Line 18-18, illustrating another embodiment of aplurality of bypass passage flow paths.

Repeat use of reference characters in the present specification anddrawings is intended to represent the same or analogous features orelements of the present invention.

DETAILED DESCRIPTION

Reference now will be made in detail to exemplary embodiments of thepresently disclosed subject matter, one or more examples of which areillustrated in the drawings. Each example is provided by way ofexplanation and should not be interpreted as limiting the presentdisclosure. In fact, it will be apparent to those skilled in the artthat various modifications and variations can be made in the presentdisclosure without departing from the scope or spirit of the presentdisclosure. For instance, features illustrated or described as part ofone embodiment can be used with another embodiment to yield a stillfurther embodiment. Thus, it is intended that the present disclosurecovers such modifications and variations as come within the scope of theappended claims and their equivalents.

As used herein, the terms “first”, “second”, and “third” may be usedinterchangeably to distinguish one component from another and are notintended to signify location or importance of the individual components.

Furthermore, the terms “upstream” and “downstream” refer to the relativedirection with respect to fluid flow in a fluid pathway. For example,“upstream” refers to the direction from which the fluid flows, and“downstream” refers to the direction to which the fluid flows.

Additionally, the terms “low,” “high,” or their respective comparativedegrees (e.g., lower, higher, where applicable) each refer to relativespeeds within an engine, unless otherwise specified. For example, a“low-pressure turbine” operates at a pressure generally lower than a“high-pressure turbine.” Alternatively, unless otherwise specified, theaforementioned terms may be understood in their superlative degree. Forexample, a “low-pressure turbine” may refer to the lowest maximumpressure turbine within a turbine section, and a “high-pressure turbine”may refer to the highest maximum pressure turbine within the turbinesection.

In general, the present subject matter is directed to a heat exchangerfor an aircraft or an associated gas turbine engine. As will bedescribed below, the heat exchanger may be configured to transfer heatbetween two or more fluids supporting the operation of the engine and/orthe aircraft. For example, the heat exchanger may be configured totransfer heat between the oil lubricating the engine and the fuelsupplied to the engine. In several embodiments, the heat exchangerincludes an inlet plenum housing defining an inlet plenum configured toreceive a fluid and an outlet plenum housing defining an outlet plenumconfigured to discharge the fluid from the heat exchanger. Furthermore,the heat exchanger includes a core configured to heat or cool a firstportion of the fluid. As such, the core defines a plurality of fluidpassages fluidly coupled to and extending from the inlet and outletplena.

Additionally, the heat exchanger includes a passive bypass.Specifically, in several embodiments, the passive bypass defines apassive bypass flow path fluidly coupled to and extending between theinlet and outlet plena. Moreover, the passive bypass flow path is inparallel with at least a portion of the core. As such, during operationof the heat exchanger, a fluid enters the inlet plenum. A first portionof this fluid flows through the fluid passages of the core to the outletplenum, thereby allowing heat to be transferred to or from this portionof the fluid. Furthermore, a second portion of the fluid entering theinlet plenum bypasses at least a portion of the core and flowscontinuously and unobstructed through the passive bypass flow path tothe outlet plenum. Thus, the passive bypass flow path is completelydevoid of valves or other devices that selectively occlude the flow offluid therethrough.

The passive bypass of the heat exchanger provides one or more technicaladvantages. More specifically, as mentioned above, conventional heatexchangers are generally oversized to maintain the desired heat transferrate while keeping the pressure drop under a threshold value. Such anoversized heat exchanger add weight to the gas turbine engine and/oraircraft on which it is installed. However, the passive bypass allows aportion of the fluid to bypass the core continuously and in anunobstructed manner (i.e., without being controlled by a valve(s)),thereby keeping the pressure drop of the fluid across the heat exchangerunder a threshold value while maintaining a sufficient heat transferrate. Thus, the passive bypass allows the disclosed heat exchanger to besmaller and lighter than conventional heat exchangers, thereby reducingthe overall weight of the gas turbine engine and/or aircraft andimproving its efficiency (e.g., fuel consumption).

Referring now to the drawings, FIG. 1 is a side view of one embodimentof an aircraft 30. As shown, in several embodiments, the aircraft 30includes a fuselage 32 and a pair of wings 34 (one is shown) extendingoutward from the fuselage 32. In the illustrated embodiment, a gasturbine engine 100 is supported on each wing 34 to propel the aircraftthrough the air during flight. Additionally, as shown, the aircraft 30includes a vertical stabilizer 36 and a pair of horizontal stabilizers38 (one is shown). However, in alternative embodiments, the aircraft 30may include any other suitable configuration, such as any other suitablenumber or type of engines.

Furthermore, the aircraft 30 may include one or more heat exchangers200. In general, the heat exchanger(s) 200 transfer heat between two ormore fluids (e.g., oil, fuel, and/or the like) supporting the operationof the aircraft 30. As will be described below, one or more heatexchangers 200 may be provided in operative association with each engine100. However, in alternative embodiments, the heat exchanger(s) 200 maybe in operative association with any other suitable component(s) of theaircraft 30.

The configuration of the aircraft 30 described above and shown in FIG. 1is provided only to place the present subject matter in an exemplaryfield of use. Thus, the present subject matter may be readily adaptableto any manner of aircraft.

FIG. 2 is a schematic cross-sectional view of one embodiment of a gasturbine engine 100. In the illustrated embodiment, the engine 100 isconfigured as a high-bypass turbofan engine. However, in alternativeembodiments, the engine 100 may be configured as a propfan engine, aturbojet engine, a turboprop engine, a turboshaft gas turbine engine, orany other suitable type of gas turbine engine.

In general, the engine 100 extends along an axial centerline 102 andincludes a fan 104, a low-pressure (LP) spool 106, and a high pressure(HP) spool 108 at least partially encased by an annular nacelle 110.More specifically, the fan 104 may include a fan rotor 112 and aplurality of fan blades 114 (one is shown) coupled to the fan rotor 112.In this respect, the fan blades 114 are circumferentially spaced apartand extend radially outward from the fan rotor 112. Moreover, the LP andHP spools 106, 108 are positioned downstream from the fan 104 along theaxial centerline 102. As shown, the LP spool 106 is rotatably coupled tothe fan rotor 112, thereby permitting the LP spool 106 to rotate the fan114. Additionally, a plurality of outlet guide vanes or struts 116circumferentially spaced apart from each other and extend radiallybetween an outer casing 118 surrounding the LP and HP spools 106, 108and the nacelle 110. As such, the struts 116 support the nacelle 110relative to the outer casing 118 such that the outer casing 118 and thenacelle 110 define a bypass airflow passage 120 positioned therebetween.

The outer casing 118 generally surrounds or encases, in serial floworder, a compressor section 122, a combustion section 124, a turbinesection 126, and an exhaust section 128. For example, in someembodiments, the compressor section 122 may include a low-pressure (LP)compressor 130 of the LP spool 106 and a high-pressure (HP) compressor132 of the HP spool 108 positioned downstream from the LP compressor 130along the axial centerline 102. Each compressor 130, 132 may, in turn,include one or more rows of stator vanes 134 interdigitated with one ormore rows of compressor rotor blades 136. Moreover, in some embodiments,the turbine section 126 includes a high-pressure (HP) turbine 138 of theHP spool 108 and a low-pressure (LP) turbine 140 of the LP spool 106positioned downstream from the HP turbine 138 along the axial centerline102. Each turbine 138, 140 may, in turn, include one or more rows ofstator vanes 142 interdigitated with one or more rows of turbine rotorblades 144.

Additionally, the LP spool 106 includes the low-pressure (LP) shaft 146and the HP spool 108 includes a high pressure (HP) shaft 148 positionedconcentrically around the LP shaft 146. In such embodiments, the HPshaft 148 rotatably couples the rotor blades 144 of the HP turbine 138and the rotor blades 136 of the HP compressor 132 such that rotation ofthe HP turbine rotor blades 144 rotatably drives HP compressor rotorblades 136. As shown, the LP shaft 146 is directly coupled to the rotorblades 144 of the LP turbine 140 and the rotor blades 136 of the LPcompressor 130. Furthermore, the LP shaft 146 is coupled to the fan 104via a gearbox 150. In this respect, the rotation of the LP turbine rotorblades 144 rotatably drives the LP compressor rotor blades 136 and thefan blades 114.

In several embodiments, the engine 100 may generate thrust to propel anaircraft. More specifically, during operation, air (indicated by arrow152) enters an inlet portion 154 of the engine 100. The fan 104 suppliesa first portion (indicated by arrow 156) of the air 152 to the bypassairflow passage 120 and a second portion (indicated by arrow 158) of theair 152 to the compressor section 122. The second portion 158 of the air152 first flows through the LP compressor 130 in which the rotor blades136 therein progressively compress the second portion 158 of the air152. Next, the second portion 158 of the air 152 flows through the HPcompressor 132 in which the rotor blades 136 therein continueprogressively compressing the second portion 158 of the air 152. Thecompressed second portion 158 of the air 152 is subsequently deliveredto the combustion section 124. In the combustion section 124, the secondportion 158 of the air 152 mixes with fuel and burns to generatehigh-temperature and high-pressure combustion gases 160. Thereafter, thecombustion gases 160 flow through the HP turbine 138 which the HPturbine rotor blades 144 extract a first portion of kinetic and/orthermal energy therefrom. This energy extraction rotates the HP shaft148, thereby driving the HP compressor 132. The combustion gases 160then flow through the LP turbine 140 in which the LP turbine rotorblades 144 extract a second portion of kinetic and/or thermal energytherefrom. This energy extraction rotates the LP shaft 146, therebydriving the LP compressor 130 and the fan 104 via the gearbox 150. Thecombustion gases 160 then exit the engine 100 through the exhaustsection 128.

As mentioned above, the aircraft 30 may include one or more heatexchangers 200 for transferring heat between fluids supporting theoperation of the aircraft 30. In this respect, a heat exchanger(s) 200may be positioned within the engine 100. For example, as shown in FIG.2, in the illustrated embodiment, the engine 100 includes a heatexchanger 200 in operative association with the gearbox 150. In such anembodiment, the heat exchanger 200 may be configured as a fuel-oil heatexchanger that transfers heat from the oil lubricating the gearbox 150to the fuel supplied to the combustion section 124. However, inalternative embodiments, the heat exchanger(s) 200 may be in operativeassociation with any other suitable component(s) of the engine 100.Moreover, in further embodiments, the engine 100 may include any othersuitable number or type of heat exchangers 200.

The configuration of the gas turbine engine 100 described above andshown in FIG. 2 is provided only to place the present subject matter inan exemplary field of use. Thus, the present subject matter may bereadily adaptable to any manner of gas turbine engine configuration,including other types of aviation-based gas turbine engines,marine-based gas turbine engines, and/or land-based/industrial gasturbine engines.

FIG. 3 is a schematic view of one embodiment of a heat exchanger 200 fora gas turbine engine and/or an aircraft. In general, the heat exchanger200 is configured to transfer heat between a first fluid and a secondfluid. As shown, the heat exchanger 200 includes an inlet plenum 202configured to receive a fluid (indicated by arrows 204). Moreover, theheat exchanger 200 includes an outlet plenum 206 configured to dischargethe fluid 204 from the heat exchanger 200. Furthermore, the heatexchanger 200 includes a core 208 fluidly coupled to and extending fromthe inlet and outlet plena 202, 206. As such, the core 208 defines aplurality of fluid passages (FIG. 5) and is configured to transfer heatbetween two or more fluids flowing therethrough. In this respect, and aswill be described below, the heat exchanger 200 includes another inletplenum and another outlet plenum fluidly coupled together by fluidpassages extending through the core 208.

Additionally, the heat exchanger 200 includes a passive bypass flow path210. Specifically, in several embodiments, the passive bypass flow path210 is fluidly coupled to and extends between the inlet and outlet plena202, 206. Moreover, the passive bypass flow path 210 is in parallel withat least a portion of the core 208. As such, during operation of theheat exchanger 200, the fluid 204 enters the inlet plenum 202. A firstportion of this fluid 204 flows through the core 208 to the outletplenum 206, thereby allowing heat to be transferred to or from thisportion of the fluid 204. Furthermore, a second portion of the fluid 204entering the inlet plenum 202 bypasses at least a portion of the core208 and flows continuously and unobstructed through the passive bypassflow path 210 to the outlet plenum 206. Thus, the passive bypass flowpath 210 is completely devoid of valves or other devices thatselectively occlude the flow of fluid therethrough.

In general, the passive bypass flow path 210 is larger than theindividual fluid passages of the core 208. In this respect, the fluid204 can flow through the passive bypass flow path 210 at a greater flowrate than though each individual fluid passage of the core 208. Thus,much less heat is transferred to or from the fluid 204 flowing throughthe passive bypass flow path 210 than the fluid passages of the core208. For example, the diameter of the passive bypass flow path 210 (orthe greatest dimension of its cross-section) may be at least twice aslarge as each individual fluid passage of the core 208, such as threetimes as large, four times as large, or five or more times as large.

The passive bypass flow path 210 of the heat exchanger 200 provides oneor more technical advantages. More specifically, as mentioned above,conventional heat exchangers are generally oversized to maintain thedesired heat transfer rate while keeping the pressure drop under athreshold value. Such an oversized heat exchanger adds weight to the gasturbine engine and/or aircraft in which it is installed. However, thepassive bypass flow path 210 allows a portion of the fluid 204 to bypassthe core 208 continuously and in an unobstructed manner (i.e., withoutbeing controlled by a valve(s)), thereby keeping the pressure drop ofthe fluid across the heat exchanger 200 under a threshold value whilemaintaining a sufficient heat transfer rate. Thus, the passive bypassflow path 210 allows the disclosed heat exchanger 210 to be smaller andlighter than conventional heat exchangers, thereby reducing the overallweight of the gas turbine engine 100 and/or aircraft 30 and improvingits efficiency (e.g., fuel consumption).

In addition, the heat exchanger 200 may be configured to transfer heatbetween any suitable fluids. For example, in one embodiment, the heatexchanger 200 may be configured to transfer heat from the oillubricating a gearbox (e.g., the gearbox 150 of the engine 100) to thefuel supplied to a combustion section of a gas turbine engine (e.g., thecombustion section 124 of a gas turbine engine 100). However, inalternative embodiments, the heat exchanger 200 may be configured totransfer heat between any other suitable fluids.

FIG. 4 is a schematic view of another embodiment of a heat exchanger 200for a gas turbine engine and/or an aircraft. Like the embodiment of theheat exchanger 200 shown in FIG. 3, the embodiment of the heat exchanger200 shown in FIG. 4 includes an inlet plenum 202, an outlet plenum 206,a core 208, and a passive bypass flow path 210. However, unlike theembodiment of the heat exchanger 200 shown in FIG. 3, the embodiment ofthe heat exchanger 200 shown in FIG. 4 includes a valved bypass 212.More specifically, the valved bypass 212 includes a valve 214 anddefines a valve bypass flow path 216 fluidly coupled to and extendingfrom the inlet plenum 202 to the outlet plenum 204. Furthermore, thevalved bypass flow path 216 is in parallel with the core 208 and thepassive bypass flow path 210. As such, when the valve 214 is at anopened position, a third portion of the fluid 204 bypasses at least aportion of the core 208 and the passive bypass flow path to flow throughthe valved bypass flow path 210 and to the outlet plenum 206. Forexample, when a pressure of the fluid 204 within the inlet plenum 202exceeds a threshold pressure value, the valve 214 may move from a closedposition to the opened position, thereby allowing the third portion ofthe fluid to flow through the valved bypass flow path 210.

FIG. 5 is a diagrammatic view of one embodiment of a heat exchanger 200for a gas turbine engine and/or an aircraft. As shown, the heatexchanger 200 includes a first fluid circuit 216 and a second fluidcircuit 218. More specifically, a first fluid flows through the firstfluid circuit 216 and a second fluid flows through the second fluidcircuit. In this respect, the heat exchanger 200 allows heat transferbetween the first and second fluids. Although FIG. 5 illustrates onlytwo fluid circuits 216, 218, the heat exchanger 200 may, in alternativeembodiments, include three or more fluid circuits allowing three or morefluids to flow through the heat exchanger 200.

As shown, the first fluid circuit 214 includes the inlet plenum 202, theoutlet plenum 206, and the passive bypass flow path 210. In thisrespect, the first fluid circuit 214 includes an inlet plenum housing218 defining the inlet plenum 202 and an outlet plenum housing 220defining the outlet plenum 206. Furthermore, the first fluid circuit 214includes a passive bypass 222 defining the passive bypass flow path 210.For example, in the illustrated embodiment, the passive bypass 222extends between the inlet plenum housing 218 and the outlet plenumhousing 220.

Additionally, the first fluid circuit 214 includes a plurality of fluidpassages 224 of the core 208. Specifically, the fluid passages 224extend from the inlet plenum 202 to the outlet plenum 206.

Moreover, the second fluid circuit 216 includes similar components tothe first fluid circuit 214. As shown, the second fluid circuit 216includes an inlet plenum housing 226 defining the inlet plenum 228 andan outlet plenum housing 230 defining the outlet plenum 232.Furthermore, the second fluid circuit 216 includes a plurality of fluidpassages 234 of the core 208. Specifically, the fluid passages 234extend from the inlet plenum 228 to the outlet plenum 232. Additionally,in the illustrated embodiment, the second fluid circuit 216 does notinclude a passive bypass. However, in alternative embodiments, thesecond fluid circuit 216 may include a passive bypass.

In operation, the heat exchanger 200 transfers heat between the fluid204 and another fluid (indicated by arrow 236). More specifically, thefluid 204 enters the inlet plenum 202 of the first fluid circuit 214. Afirst portion of this fluid 204 flows through the fluid passages 224 ofthe core 208 to the outlet plenum 206 of the first fluid circuit 214.Simultaneously, the fluid 236 enters the inlet plenum 228 of the secondfluid circuit 216. The fluid 236 then flows through the fluid passages234 of the core 208 to the outlet plenum 206 of the second fluid circuit216. The fluid passages 224, 234 are near each other to allow heattransfer between the fluids 204, 236. Additionally, as mentioned above,a second portion of the fluid 204 entering the inlet plenum 202 of thefirst fluid circuit 214 bypasses the core 208 and flows continuously andunobstructed through the passive bypass flow path 210 to the outletplenum 206.

FIG. 6 is a partial cross-sectional view of the heat exchanger 200,illustrating the inlet plenum 202, the outlet plenum 206, and thepassive bypass flow path 210. As shown, the heat exchanger 200 includesa baffle 238 positioned within the inlet plenum 202 such that the baffle238 partially defines the inlet plenum 202 and partially defines thepassive bypass flow path 210. For example, in the illustratedembodiment, the baffle 238 is arcuate. However, in alternativeembodiments, the baffle 238 may have any other suitable configuration.In operation, the baffle 238 divides the fluid 204 entering the inletplenum 202 into a first portion 240 and a second portion 242. The firstportion 240 of the fluid 204 flows from the inlet plenum 202 through thefluid passages 224 of the core 208 and into the outlet plenum 206.Conversely, the baffle 238 directs the second portion 242 of the fluid204 into the passive bypass flow path 210. As such, the second portion242 of the fluid 204 flows through the passive bypass flow path 210 tothe outlet plenum 206, thereby bypassing the core 208. Additionally, thearcuate shape of the baffle 238 imparts a centripetal force on thesecond portion 242 of the fluid 204 flowing through the passive bypassflow path 210. Such a force directs most of the particulates 244 withinthe fluid 204 into the passive bypass flow path 210, thereby reducingthe likelihood that the particulates 244 occlude a fluid passage(s) 224of the core 208.

The heat exchanger 200 may have any number of passive bypass flow path210 and such passive bypass flow path(s) 210 may have any suitablecross-sectional shape. For example, as shown in FIG. 7, in oneembodiment, the heat exchanger 200 includes two passive bypass flowpaths 210, with such flow paths 210 having a kidney-shapedcross-sectional shape. As shown in FIG. 8, in another embodiment, theheat exchanger 200 includes a single passive bypass flow path 210, withsuch flow path 210 having an elliptical cross-sectional shape. Moreover,as shown in FIG. 9, in a further embodiment, the heat exchanger 200includes a single passive bypass flow path 210, with such flow path 210having a circular cross-sectional shape.

FIGS. 10 and 11 illustrate another embodiment of the heat exchanger 200.Specifically, FIG. 10 is a partial top view of the heat exchanger 200.Additionally, FIG. 11 is a cross-sectional view of the heat exchanger200 generally taken about Line 11-11 in FIG. 10. Like the embodiment ofthe heat exchanger 200 shown in FIGS. 5 and 6, the embodiment of theheat exchanger 200 shown in FIGS. 10 and 11 includes an inlet plenumhousing 218 defining an inlet plenum 202, an outlet plenum housing 220defining an outlet plenum 206, and a core 208. Moreover, like theembodiment of the heat exchanger 200 shown in FIGS. 5 and 6, theembodiment of the heat exchanger 200 shown in FIGS. 10 and 11 includes apassive bypass 222 extending between the inlet and outlet plenumhousings 218, 220, with the passive bypass 222 defining a passive bypassflow path 210 fluidly coupling the inlet and outlet plena 202, 206.Moreover, the passive bypass flow path 210 is in parallel with the core208.

However, unlike the embodiment of the heat exchanger 200 shown in FIGS.5 and 6, in the embodiment of the heat exchanger 200 shown in FIGS. 10and 11, the passive bypass 222 at least partially surrounds the inletplenum 202 (and the inlet plenum housing 218). More specifically, insuch an embodiment, the inlet plenum housing 218 includes a first ornarrowed portion 246 and a second portion or enlarged portion 248positioned downstream of the first portion 246, with the first portionhaving a smaller diameter than the second portion 248. Furthermore, insome embodiments, the passive bypass 222 at least partially surroundsthe first or narrowed portion 246 of the inlet plenum housing 218.Additionally, in such an embodiment, the inlet plenum housing 218defines a plurality of circumferentially spaced apart bypass inlets 250fluidly coupling the inlet plenum 202 and the passive bypass flow path210. As such, the bypass inlets 250 allow the second portion 242 of thefluid 204 to flow radially outward from the inlet plenum 202 into thepassive bypass flow path 210. In one embodiment, the bypass inlets 250are non-uniformly circumferentially spaced apart from each other and arenon-uniformly sized to allow the second portion 242 of the fluid 204 toflow into the passive bypass flow path 210 at a uniform rate around itscircumference.

FIGS. 12 and 13 illustrate another embodiment of the heat exchanger 200.Specifically, FIG. 12 is a partial top view of the heat exchanger 200.Additionally, FIG. 13 is a cross-sectional view of the heat exchanger200 generally taken about Line 13-13 in FIG. 12. Like the embodiment ofthe heat exchanger 200 shown in FIGS. 10 and 11, the embodiment of theheat exchanger 200 shown in FIGS. 12 and 13 includes an inlet plenumhousing 218 defining an inlet plenum 202 and having a first or narrowedportion 246 and a second portion or enlarged portion 248 positioneddownstream of the first portion 246, with the first portion having asmaller diameter than the second portion 248. Moreover, like theembodiment of the heat exchanger 200 shown in FIGS. 10 and 11, theembodiment of the heat exchanger 200 shown in FIGS. 12 and 13 includes apassive bypass 222 at least partially surrounding the inlet plenum 202(and the inlet plenum housing 218). However, unlike the embodiment ofthe heat exchanger 200 shown in FIGS. 10 and 11, in the embodiment ofthe heat exchanger 200 shown in FIGS. 12 and 13, the passive bypass 222at least partially surrounds the second or enlarged portion 248 of theinlet plenum 202.

FIGS. 14 and 15 illustrate yet another embodiment of the heat exchanger200. Specifically, FIG. 14 is a partial top view of the heat exchanger200. Additionally, FIG. 15 is a cross-sectional view of the heatexchanger 200 generally taken about Line 15-15 in FIG. 14. Like theembodiments of the heat exchanger 200 shown in FIGS. 5, 6, and 10-13,the embodiment of the heat exchanger 200 shown in FIGS. 14 and 15includes an inlet plenum housing 218 defining an inlet plenum 202, anoutlet plenum housing 220 defining an outlet plenum 206, and a core 208.Moreover, like the embodiments of the heat exchanger 200 shown in FIGS.5, 6, and 10-13, the embodiment of the heat exchanger 200 shown in FIGS.14 and 15 includes a passive bypass 222 extending between the inlet andoutlet plenum housings 218, 220, with the passive bypass 222 defining apassive bypass flow path 210 fluidly coupling the inlet and outlet plena202, 206.

However, unlike the embodiments of the heat exchanger 200 shown in FIGS.5, 6, and 10-13, in the embodiment of the heat exchanger 200 shown inFIGS. 14 and 15, the passive bypass flow path 210 extends the core 208.Specifically, in the illustrated embodiment, the passive bypass flowpath 212 extends centrally through the core 208 such that the fluidpassages 224, 234 surround the passive bypass flow path 210. Suchpositioning of the passive bypass flow path 212 may prevent ice frombuilding up on the core 208 in certain instances.

FIG. 16 illustrates another embodiment of the heat exchanger 200. Likethe embodiments of the heat exchanger 200 shown in FIGS. 5, 6, and10-15, the embodiment of the heat exchanger 200 shown in FIG. 16includes an inlet plenum housing 218 defining an inlet plenum 202, anoutlet plenum housing 220 defining an outlet plenum 206, and a core 208.Moreover, like the embodiments of the heat exchanger 200 shown in FIGS.5, 6, and 10-13, the embodiment of the heat exchanger 200 shown in FIGS.14 and 15 includes a passive bypass 222 extending between the inlet andoutlet plenum housings 218, 220, with the passive bypass 222 defining apassive bypass flow path 210 fluidly coupling the inlet and outlet plena202, 206.

However, unlike the embodiments of the heat exchanger 200 shown in FIGS.5, 6, and 10-15, in the embodiment of the heat exchanger 200 shown inFIG. 16, the passive bypass flow path 210 extends from the core 208 tothe outlet plenum 206. Specifically, the passive bypass flow path 210may extend from one or more of the fluid passages 224 of the core 208 tothe outlet plenum 206. In this respect, the second portion 242 of thefluid 204 flows through an upstream portion of the core 208 beforeentering the passive bypass flow path, thereby bypassing a downstreamportion of the core 208.

FIGS. 17-19 illustrate a further embodiment of the heat exchanger 200.

Specifically, FIG. 17 is a partial top view of the heat exchanger 200.Moreover, FIG. 18 is a cross-sectional view of the heat exchanger 200generally taken about Line 18-18 in FIG. 17, illustrating one embodimentof a plurality of bypass passage flow paths 210. Additionally, FIG. 19is a cross-sectional view of the heat exchanger 200 generally takenabout Line 18-18 in FIG. 17, illustrating another embodiment of aplurality of bypass passage flow paths 210. Like the embodiment of theheat exchanger 200 shown in FIGS. 14 and 15, the embodiment of the heatexchanger 200 shown in FIGS. 16-19 includes an inlet plenum housing 218defining an inlet plenum 202, an outlet plenum housing 220 defining anoutlet plenum 206, and a core 208. Moreover, like the embodiment of theheat exchanger 200 shown in FIGS. 14 and 15, the embodiment of the heatexchanger 200 shown in FIGS. 16-19 includes a passive bypass flow path210 extending through the core 208 between the inlet and outlet plenumhousings 218, 220.

However, unlike the embodiment of the heat exchanger 200 shown in FIGS.14 and 15, in the embodiment of the heat exchanger 200 shown in FIG. 18,three passive bypass flow paths 210 are positioned adjacent to theexterior of the core 208. That is, the three passive bypass flow paths210 are positioned between the fluid passages 224 and the exterior ofthe core 208.

Additionally, in the embodiment of the heat exchanger 200 shown in FIG.19, three passive bypass flow paths 210 are positioned centrally withinthe core 208, but only partially surrounded by the fluid passages 224.However, in alternative embodiments, the heat exchanger 200 may definemore or fewer passive bypass flow paths 210.

The FIGS. illustrate only certain numbers (e.g., two or three) of fluidpassages 224, 234 through the core 208 for purposes of clarity. However,the core 208 may define any suitable number of fluid passages 224, 234,such as fifty fluid passages 224, 234; one hundred fluid passages 224,234; or more fluid passages 224, 234.

Additionally, in several embodiment, the heat exchanger 200 may beintegrally formed as a single monolithic component, such as via asuitable additive printing or manufacturing process. However, inalternative embodiments, the heat exchanger 200 may be formed as anysuitable number of component that are assembled together and/or via anyof suitable manufacturing process.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they include structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal language of the claims.

Further aspects of the invention are provided by the subject matter ofthe following clauses:

A heat exchanger for an aircraft, the heat exchanger comprising: aninlet plenum housing defining an inlet plenum configured to receive afluid; an outlet plenum housing defining an outlet plenum configured todischarge the fluid from the heat exchanger; a core configured to heator cool a first portion of the fluid, the core defining a plurality offluid passages fluidly coupled to and extending from the inlet plenum tothe outlet plenum; and a passive bypass defining a passive bypass flowpath fluidly coupled to and extending between the inlet plenum and theoutlet plenum, the passive bypass flow path being in parallel with atleast a portion of the core such that a second portion of the fluidbypasses at least a portion of the core and flows continuously andunobstructed through the passive bypass flow path to the outlet plenum.

The heat exchanger of one or more of these claim clauses, furthercomprising: a valved bypass including a valve and defining a valvebypass flow path fluidly coupled to and extending from the inlet plenumto the outlet plenum, the valved bypass flow path being in parallel withthe core and the passive bypass flow path such that, when the valve isat an opened position, a third portion of the fluid bypasses at least aportion of the core and flows through the valved bypass flow path to theoutlet plenum.

The heat exchanger of one or more of these claim clauses, wherein, whena pressure of the fluid within the inlet plenum exceeds a thresholdpressure value, the valve moves from a closed position to the openedposition.

The heat exchanger of one or more of these claim clauses, furthercomprising: a baffle positioned within the inlet plenum and partiallydefining the passive bypass flow path such that the baffle splits thefluid entering the inlet plenum into the first and second portions.

The heat exchanger of one or more of these claim clauses, wherein thebaffle has an arcuate shape.

The heat exchanger of one or more of these claim clauses, wherein thepassive bypass flow path has at least one of a kidney-shapedcross-sectional shape, an elliptical cross-sectional shape, or acircular cross-sectional shape.

The heat exchanger of one or more of these claim clauses, wherein aportion of the passive bypass surrounds the inlet plenum such that thesecond portion of the fluid flows radially outward from the inlet plenuminto the passive bypass flow path.

The heat exchanger of one or more of these claim clauses, wherein theinlet plenum housing defines a plurality of circumferentially spacedapart bypass inlets fluidly coupling the inlet plenum and the passivebypass flow path.

The heat exchanger of one or more of these claim clauses, wherein thebypass inlets are non-uniformly circumferentially spaced apart from eachother.

The heat exchanger of one or more of these claim clauses, wherein theinlet plenum includes a first portion and a second portion positioneddownstream of the first portion, the first portion having a smallerdiameter than the second portion, the passive bypass surrounding thefirst portion of the inlet plenum.

The heat exchanger of one or more of these claim clauses, wherein theinlet plenum includes a first portion and a second portion positioneddownstream of the first portion, the first portion having a smallerdiameter than the second portion, the passive bypass surrounding thesecond portion of the inlet plenum.

The heat exchanger of one or more of these claim clauses, wherein thepassive bypass flow path extends through the core.

The heat exchanger of one or more of these claim clauses, wherein thepassive bypass flow path extends centrally through the core such thatthe plurality of fluid passages surrounds the passive bypass flow path.

The heat exchanger of one or more of these claim clauses, wherein thepassive bypass path is positioned between the plurality of fluidpassages and an exterior of the core.

The heat exchanger of one or more of these claim clauses, wherein thepassive bypass flow path comprises a plurality of passive bypass flowpaths extending through the core.

The heat exchanger of one or more of these claim clauses, wherein thepassive bypass extends from the core to the outlet plenum housing suchthat the second portion of fluid flows from the core through the passivebypass flow path to the outlet plenum.

The heat exchanger of one or more of these claim clauses, wherein theheat exchanger is integrally formed.

A gas turbine engine, comprising: a compressor; a combustor; a turbine;a heat exchanger in operative association with at least one of thecompressor, the combustor, or the turbine, the heat exchangercomprising: an inlet plenum housing defining an inlet plenum configuredto receive a fluid; an outlet plenum housing defining an outlet plenumconfigured to discharge the fluid from the heat exchanger; a coreconfigured to heat or cool a first portion of the fluid, the coredefining a plurality of fluid passages fluidly coupled to and extendingfrom the inlet plenum to the outlet plenum; and a passive bypassdefining a passive bypass flow path fluidly coupled to and extendingbetween the inlet plenum and the outlet plenum, the passive bypass flowpath being in parallel with at least a portion of the core such that asecond portion of the fluid bypasses at least a portion of the core andflows continuously and unobstructed through the passive bypass flow pathto the outlet plenum.

The gas turbine engine of one or more of these claim clauses, furthercomprising: a valved bypass including a valve and defining a valvebypass flow path fluidly coupled to and extending from the inlet plenumto the outlet plenum, the valved bypass flow path being in parallel withthe core and the passive bypass flow path such that, when the valve isat an opened position, a third portion of the fluid bypasses at least aportion of the core and flows through the valved bypass flow path to theoutlet plenum.

The gas turbine engine of one or more of these claim clauses, wherein,when a pressure of the fluid within the inlet plenum exceeds a thresholdpressure value, the valve moves from a closed position to the openedposition.

What is claimed is:
 1. A heat exchanger for an aircraft, the heatexchanger comprising: an inlet plenum housing defining an inlet plenumconfigured to receive a fluid; an outlet plenum housing defining anoutlet plenum configured to discharge the fluid from the heat exchanger;a core configured to heat or cool a first portion of the fluid, the coredefining a plurality of fluid passages fluidly coupled to and extendingfrom the inlet plenum to the outlet plenum; and a passive bypassdefining a passive bypass flow path fluidly coupled to and extendingbetween the inlet plenum and the outlet plenum, the passive bypass flowpath being in parallel with at least a portion of the core such that asecond portion of the fluid bypasses at least a portion of the core andflows continuously and unobstructed through the passive bypass flow pathto the outlet plenum.
 2. The heat exchanger of claim 1, furthercomprising: a valved bypass including a valve and defining a valvebypass flow path fluidly coupled to and extending from the inlet plenumto the outlet plenum, the valved bypass flow path being in parallel withthe core and the passive bypass flow path such that, when the valve isat an opened position, a third portion of the fluid bypasses at least aportion of the core and flows through the valved bypass flow path to theoutlet plenum.
 3. The heat exchanger of claim 2, wherein, when apressure of the fluid within the inlet plenum exceeds a thresholdpressure value, the valve moves from a closed position to the openedposition.
 4. The heat exchanger of claim 1, further comprising: a bafflepositioned within the inlet plenum and partially defining the passivebypass flow path such that the baffle splits the fluid entering theinlet plenum into the first and second portions.
 5. The heat exchangerof claim 4, wherein the baffle has an arcuate shape.
 6. The heatexchanger of claim 5, wherein the passive bypass flow path has at leastone of a kidney-shaped cross-sectional shape, an ellipticalcross-sectional shape, or a circular cross-sectional shape.
 7. The heatexchanger of claim 1, wherein a portion of the passive bypass surroundsthe inlet plenum such that the second portion of the fluid flowsradially outward from the inlet plenum into the passive bypass flowpath.
 8. The heat exchanger of claim 7, wherein the inlet plenum housingdefines a plurality of circumferentially spaced apart bypass inletsfluidly coupling the inlet plenum and the passive bypass flow path. 9.The heat exchanger of claim 8, wherein the bypass inlets arenon-uniformly circumferentially spaced apart from each other.
 10. Theheat exchanger of claim 8, wherein the inlet plenum includes a firstportion and a second portion positioned downstream of the first portion,the first portion having a smaller diameter than the second portion, thepassive bypass surrounding the first portion of the inlet plenum. 11.The heat exchanger of claim 8, wherein the inlet plenum includes a firstportion and a second portion positioned downstream of the first portion,the first portion having a smaller diameter than the second portion, thepassive bypass surrounding the second portion of the inlet plenum. 12.The heat exchanger of claim 1, wherein the passive bypass flow pathextends through the core.
 13. The heat exchanger of claim 12, whereinthe passive bypass flow path extends centrally through the core suchthat the plurality of fluid passages surrounds the passive bypass flowpath.
 14. The heat exchanger of claim 12, wherein the passive bypasspath is positioned between the plurality of fluid passages and anexterior of the core.
 15. The heat exchanger of claim 12, wherein thepassive bypass flow path comprises a plurality of passive bypass flowpaths extending through the core.
 16. The heat exchanger of claim 1,wherein the passive bypass extends from the core to the outlet plenumhousing such that the second portion of fluid flows from the corethrough the passive bypass flow path to the outlet plenum.
 17. The heatexchanger of claim 1, wherein the heat exchanger is integrally formed.18. A gas turbine engine, comprising: a compressor; a combustor; aturbine; a heat exchanger in operative association with at least one ofthe compressor, the combustor, or the turbine, the heat exchangercomprising: an inlet plenum housing defining an inlet plenum configuredto receive a fluid; an outlet plenum housing defining an outlet plenumconfigured to discharge the fluid from the heat exchanger; a coreconfigured to heat or cool a first portion of the fluid, the coredefining a plurality of fluid passages fluidly coupled to and extendingfrom the inlet plenum to the outlet plenum; and a passive bypassdefining a passive bypass flow path fluidly coupled to and extendingbetween the inlet plenum and the outlet plenum, the passive bypass flowpath being in parallel with at least a portion of the core such that asecond portion of the fluid bypasses at least a portion of the core andflows continuously and unobstructed through the passive bypass flow pathto the outlet plenum.
 19. The gas turbine engine of claim 18, furthercomprising: a valved bypass including a valve and defining a valvebypass flow path fluidly coupled to and extending from the inlet plenumto the outlet plenum, the valved bypass flow path being in parallel withthe core and the passive bypass flow path such that, when the valve isat an opened position, a third portion of the fluid bypasses at least aportion of the core and flows through the valved bypass flow path to theoutlet plenum.
 20. The gas turbine engine of claim 19, wherein, when apressure of the fluid within the inlet plenum exceeds a thresholdpressure value, the valve moves from a closed position to the openedposition.